High capacity communication performed by means of wireless transmissions is today a common phenomenon.
The development and deployment of so called cellular network and similar have been particularly successful. A cellular network is a radio network made up of a number of radio cells (or just cells) each served by a fixed transmitter, known as a cell site or base station. The cells are used to cover different areas in order to provide radio coverage over a wider area than the area of one cell. Cellular networks are inherently asymmetric with a set of fixed main transceivers each serving a cell and a set of distributed (generally, but not always, mobile) transceivers which provide services to the network's users.
The most common example of a cellular network is a mobile phone (cell phone) network. A mobile phone is a portable telephone which receives or makes calls through a cell site (base station). Radio waves are used to transfer signals between the cell cite and the cell phone.
There are a number of different cellular technologies, including but not limited to: Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Evolution-Data Optimized (EV-DO), Enhanced Data Rates for GSM Evolution (EDGE), Digital Enhanced Cordless Telecommunications (DECT), Digital AMPS (IS-136/TDMA), Integrated Digital Enhanced Network (iDEN) and similar.
The WCDMA in particular is a type of Third Generation (3G) cellular network using the higher speed transmission protocol e.g. provided in the Japanese Freedom of Mobile Multimedia Access systems (FOMA), which is the brand name for the 3G services being offered by Japanese mobile phone operator NTT DoCoMo. The WCDMA is also used as the underlying air interface in the Universal Mobile Telecommunications System (UMTS) being standardized by the Third Generation Partnership Project (3GPP).
More technically, WCDMA is a wideband spread-spectrum mobile air interface that utilizes the direct-sequence spread spectrum method of asynchronous code division multiple access to achieve higher speeds and support more users compared to the implementation of time division multiplexing (TDMA) used by 2G GSM networks.
In release 6 of the 3GPP WCDMA specifications, support for high speed uplink packet data transmission (Enhanced Uplink, EUL) from the User Equipment (UE) to the base station (i.e. Node B) was improved by means of a new uplink transport channel, Enhanced Dedicated Channel (E-DCH) being added to the ordinary Dedicated Channel (DCH) defined in the UMTS release 99 (R99). The E-DCH supports higher data rates, Node B HARQ with soft combining and a fast Node B scheduling.
It is expected that the EUL eventually will replace ordinary UMTS release 99 (R99) uplink solutions, at least in hot spots and for bit rate demands that R99 solutions cannot cope with. Examples of this might be that VoIP (Voice over Internet Protocol, VoIP) replaces CS speech (Circuit Switched, CS), and that services requiring higher bit rates for example to cope with photo and video upload, are/will be deployed on E-DCH instead of R99 DCH.
As is well known, the DCH comprises a Dedicated Physical Control Channel (DPCCH) and a Dedicated Physical Data Channel (DPDCH). The DPCCH is the physical channel on the radio interface (Uu) on which the physical layer (layer 1) control signaling is transmitted, both on the uplink by the User Equipment (UE) to the Node B (the base transceiver station) and on the downlink by the Node B to the UE. Similarly, the DPDCH is the physical channel on the radio interface (Uu) on which the payload (e.g. IP data, voice etc) as well as higher layer signalling (e.g. Radio Resource Control, RRC and Non Access Stratum, NAS signalling) is transmitted both, on the uplink by the UE to the Node B and on the downlink by the Node B to the UE.
Similarly, it is also well known that the E-DCH comprises an Enhanced Dedicated Physical Control Channel (E-DPCCH) and an Enhanced Dedicated Physical Data Channel (E-DPDCH). The E-DPCCH and E-DPDCH of the E-DCH correspond to the DPCCH and DPDCH respectively of the DCH.
Now, according to the 3GPP standards a Transport Format Combination (TFC) has to be selected for a DCH. Similarly, an Enhanced Transport Format Combination (E-TFC) has to be selected for an E-DCH. As is well known, the transport format (TFC, E-TFC) determines the amount of data that can be sent during one transmission time interval by the control channel (DPCCH, DPDCH) and the data channel (E-DPCCH, E-DPDCH) forming the transport channel (DCH, E-DCH).
Typically, a Transport Format Combination (TFC; E-TFC) is selected according to a selection mechanism operating on network parameters indicative of the operational conditions of the control channel (DPCCH, E-DPCCH) and the data channel (DPDCH, E-DPDCH) and an array or a table or similar having a plurality of entries (e.g. 0-127 positions or similar). Each entry is represented and/or pointed out by a Transport Format Combination Indicator (TFCI, E-TFCI)
FIG. 5 is a schematic illustration of an exemplifying E-TFC table comprising 128 entries, wherein each entry comprises Bit-Rate Information y1-y128 comprising information about the bit-rate that can be supported and used by the data channel (E-DPDCH) of the transport channel (E-DCH) in a particular operational environment.
The Bit-Rate Information may e.g. comprise information about the transport block size, number of codes, spreading factor and similar to be used for the data channel E-DPDCH, and/or indicate the power ratio for the E-DPDCH and the DPCCH, the modulation to be used and/or the error correction to be used, or some other indication that separately or in combination with other indications in the Bit-Rate information can be used to directly or indirectly indicate the bit-rate for the data channel (E-DPDCH). Indeed, this does not preclude that the Bit-Rate information may comprise one or several indications that directly define the bit-rate for the data channel (E-DPDCH).
The selection of an E-TFC in an E-TFC table or similar as briefly indicated above is well known from the 3GPP specification and by those skilled in the art and it needs no further description. However, some details relevant to embodiments of the present invention will be briefly elaborated below.
The procedures for selecting an E-TFC e.g. described in the 3GPP specification TS 25.133 V6.20 (2007-12) (see chapter 6.4 Transport Format Combination Selection in UE), brings that the available power to be used by the E-DCH data channel (E-DPDCH), normalized with the DPCCH power, can be written as:NRPMj=(PMax,j−PDPCCH−PDPDCH−PHS-DPCCH−PE-DPCCH)/PDPCCH  (1)wherein,                NRPMj is the Normalised Remaining Power Margin,        PMax,j is the maximum UE transmitter power for E-TFC j,        PDPCCH represents an estimate of the current UE DPCCH power,        PDPDCH is the estimated DPDCH transmit power (based on PDPCCH and the gain factors from the TFC selection that has already been made),        PHS-DPCCH represents estimated High-Speed DPCCH transmit power based on the maximum HS-DPCCH gain factor based on PDPCCH and the most recent signalled values of the power adjustment factor with respect to ACK, NACK and CQI,        PE-DPCCH is the estimated E-DPCCH transmit power, based on PDPCCH and the E-DPCCH gain factor calculated using the most recent signalled reference power value of E-DPCCH.        
All powers are considered in linear power units, and special care must be taken in case of compressed mode.
It should further be noted that the power for e.g. the DPDCH can be written as:
                                          P            DPDCH                    =                                                    β                d                2                                            β                c                2                                      ⁢                          P              DPCCH                                      ,                            (        2        )            wherein βc, βd represents power offset factor for DPCCH, DPDCH, respectively.
Furthermore, by using (2), (1) can be rewritten as:
                                                                        NRPM                j                            =                            ⁢                                                (                                                                                                                                          PMax                            j                                                    -                                                      P                            DPCCH                                                    -                                                      P                            DPDCH                                                    -                                                                                                                                                                                          P                                                          HS                              -                              DPCCH                                                                                -                                                      P                                                          E                              -                              DPCCH                                                                                                                                                            )                                /                                  P                  DPCCH                                                                                                                        =                                ⁢                                                                            PMax                      j                                                              P                      DPCCH                                                        -                                                                                    β                        c                        2                                            +                                              β                        d                        2                                            +                                              β                        hs                        2                                            +                                              β                        ec                        2                                                                                    β                      c                      2                                                                                  ,                                                          (        3        )            wherein βec and βhs represents power offset factor for E-DPCCH and HS-DPCCH, respectively.
Omitting the HS-part (with the assumption of no parallel HS traffic or that the HS channels are not a significant part of the maximum possible UE power) and E-DPCCH due to rather low power and simplicity, and assuming that NRPM corresponds to the maximum value of βed2/βc2, you have that:
                    NRPMj        =                                            β              ed              2                                      β              c              2                                =                                                    PMax                j                                            P                DPCCH                                      -                                                            β                  c                  2                                +                                  β                  d                  2                                                            β                c                2                                                                        (        4        )            where βed is the power offset factor for E-DPDCH.
So, in a scenario were you know the power offset factors βc, βd as well as the maximum power PMax,j (i.e. the maximum available/allowed power for all above mentioned channels) and the control power level PDPCCH, you can calculate the remaining normalized power that the E-DPDCH can use. With some simplifications, this is the calculation scheme for the E-TFC selection mechanism, where the relation βed2/βc2 corresponds to a specific E-TFC comprising Bit-Rate Information corresponding to the bit-rate that can be supported and used by the E-DPDCH as previously described.
It should be emphasised that the calculation scheme for the E-TFC selection implying a certain E-DPDCH bit-rate as described above assumes a possible parallel operation of DCH and E-DCH, which means that the WCDMA network have been configured to let βd, βed and βc coexist given a particular available remaining power margin NRPMj to be used by the E-DPDCH. Henceforth, power offset factors that reflect a DCH and an E-DCH existing/deployed in parallel will be denoted as βd,E-DCH, βed,E-DCH and βc,E-DCH, respectively. Similarly, power offset factor representing a scenario with only DCH present will henceforth thus be denoted as βd,DCH and βc,DCH, respectively.
Now, before deploying EUL with a DCH and an E-DCH in parallel, the network planning would benefit from a prediction of the future E-DPDCH bit-rate that can be obtained when the single DCH in the UMTS R99 is replaced by EUL operating a DCH and E-DCH in parallel. Here, it would be tempting to use the above calculation scheme for the E-TFC selection to predict an E-DPDCH bit-rate. However, the existing R99 WCDMA network is configured so that only βd,DCH and βc,DCH coexists in a preferred and/or optimized manner. There is consequently no remaining power margin NRPMj to be used by an E-DPDCH, i.e. there is no βed,E-DCH offset in the exiting R99 network. It follows that the above calculation scheme, e.g. represented by the expression (4), cannot properly be used to predict a contemplated selection E-TFC and thus a future E-DPDCH bit-rate. Also, the used power for the PDPCCH will not apply for EUL. Moreover, a further reason to distinguish between e.g. βc,DCH and βd,DCH on one hand and on the other hand βc,E-DCH and βd,E-DCH, is that you might need to set some of the power offsets differently as E-DCH is deployed; the power relation e.g. between DPCCH and DPDCH in case E-DCH is deployed will not necessarily be similar to the corresponding relation present when only DCH is present. Further, when an E-DCH is used the quality target used by the power control might be changed which makes the DPCCH power in (4) incorrect.
Nevertheless, there are other methods that can be used to predict the E-DPDCH bit-rate for a given area or position in a cell. Such methods often use theoretical pen and paper calculations or dynamical/semi-dynamical or static system simulations, or similar. These methods provide good accuracy and catch many detailed system aspects, but they require access to proper input data (e.g. cell deployment information and user mobility information etc) for the specific area, but also significant computational time. Additionally, to build and maintain detailed simulation tools requires specific competence that a person on the field not necessarily holds.
It would therefore be fruitful to have some kind of E-DPDCH bit-rate estimating/prediction method that could be used in field, not requiring significant CPU time and specialized radio algorithm competence. Such methodology would preferably use such input information that already is available in the network prior to EUL deployment.